Shellaclike product and process of making the same



July 15, 1930. A. w. BURWELL SHELLAC LIKE PRODUCT AND PROCESS OF MAKING THE SAME Filed Dec. 20, 1926 I or Warw- Cqnde/M'er e M .1 M 0 E We Pw 6 w, i Mi r $8 dbkoznuaa.

- Y density of 33 Patented July 15, 1930 UNITED STATES PATENT OFFICE ARTHUR w. BURWELL, or NIAGARA FALLS, NEW YORK, ASSIGNOR TO ALOX CHEMICAL CORPORATION, OF NEW YORK, N. Y. A CORPORATION OF NEW YORK SHELLACLIKE PRODUCT AND PROCESS OF MAKING THE SAME Application filed December 20, 1926.

This invention relates to shellac-like products having many of the characteristics of natural shellac, to a process of making the same, and to compositions containing these products.

I have found that, by the liquid-phase oxi dation, under controlled conditions, of hydrocarbons or mixtures thereof such as those occurring in petroleum oils, obtained a variety of oxidation products ineluding formic acid, light ketones and aldehydes, heavy ketones and aldehydes, waterinsoluble carboxylic acids which are soluble in the hydrocarbon mixture, and water-insoluble hydroxy-carboxylic acids which are insoluble inthe hydrocarbon mixture.

An object of the present invention is to provide petroleum hydrocarbon oxidation products which consist essentially of saponifiable, water-insoluble hydroxy-carbox lie acids insoluble in petroleum hydrocar on mixtures. More specifically, the present invention concerns the shellac-like products obtained by the controlled continent or Pennsylvania petroleum distil lates having a density of from about 40 to about 36 Baum, i. e., the so-called fuel oil distillates, although I have found that these products are obtainable from other petroleum distillates-than those just mentioned, such as, for example the distillates having a to 18 Baum.

The process of making these shellac-like products consists generally in the liquidphase oxidation of hydrocarbons or mixtures thereof, under such conditions as to promote the formation of saponifiable, water-insoluble, petroleum-insoluble hydroxy-carboxylic acids and the isolation of the said acids from the partially oxidized mass.

Although this invention is not restricted to the use of any particular hydrocarbon or mixture of hydrocarbons, I prefer to use as starting material the lowest cost petroleum distillate obtainable. For example, the socalled fuel oil distillate having a density of 4036 Baum, has been foundto be advantageous, due to its relatively low cost. In general, it may be stated that the proneness to form petroleum-insoluble hydroxythere may be.

oxidation of mid Serial No. 156,052.

carboxylic acids is particularly inherent in those petroleum hydrocarbon mixtures which are of relatively higher specific gravity and which contain a minimum of crystallizable bodies (e. g. wax).

The invention will be described and illustrated hereinafter by reference to a batch process, it being understood, however, that the procedure may be made continuous, as shall be explained.

In the accompanying drawing there is shown diagrammatically one form of apparatus suitable for use in carrying out the process of the invention. 1

The oxidation step proper takes place in an upright cylindrical reaction vessel or oxidizer 1, which may be, for example, about 5 feet in diameter and about 16 to 18 feet in height. The oxidizer 1 may be made of any suitable material such as iron or steel and should be capable of withstanding pressures up to 350 pounds per square inch. Preferably, the oxidizer 1 should be made of or lined withmaterial which is resistant to the corrosive action of the reaction mixture; for example, provided with an inner shell of aluminum 2. The oxidizer is provided at a point near its lower end with a tight coil 3 which serves as a heating or.cooling coil as required. Suitable means, not illustrated, such as a jacket surrounding the oxidizer, also may be used to control the temperature of the oxidation reaction. At a point between the lower end of the oxidizer 1 and the tight coil 3 is an air spray pipe 4 connected by pipe line 5 to an air compressor 6. A11- spray pipe 4 is so designed that air is e ected from it in the form of fine bubbles. 7, S and 9 are a valved hydrocarbon supply pipe, a valved'liquid discharge pipe and a valved gas discharge pipe, respectively. 10 is a pressure gauge, and 11 is a\thermometer. 12 is a separating tank fed by the valved liquid discharge pipe 8 leading from the oxidizer 1; said tank being provided with agi tating means '(not shown).

- From the bottom of the separating tank 12 extend the valved conduits 13 and 14 for the transference of'fluids to the still 17 and to theacid water tank21 respectively. 16 is a valved supply pipe for conducting 'water to the separating tank 12. 18 is a condenser, 19 is a distillate receiver and 20 is a vacuum pump. 22 is a valved conduit for admitting air, steam, or the like, to the still 17 23 1s a valved conduit for the transference of distillate from the distillate receiver 19 to the valved conduit 14 or (as indicated hereinafter) to a suitable receiver for distillate which is to be further worked up. 24 is a swing suction or decantation device in separating tank 12. 25 is a valved conduit for the transfer of residue from still 17. 26 is a conduit communicating between the top portion of the still 17 and distillate receiver 19 through the condenser 18.

The process is carried out in the apparatus illustrated as follows: y

A petroleum hydrocarbon mixture, such as, for example, the 4036 B. fuel oil distillate above mentioned, is charged into the oxidizer 1, a small amount of'an oxidizing catalyst or exciter of oxidation, such as a compound of manganese copper or iron,- say manganese oleate,amounting to about 0.1 percent of the weight of the oil is added and the mixture heated up to a temperature in the neighborhood of 120 C. or higher, preferably to about 135140 C., and an oxidizing gas, preferably air, is supplied through the spray pipe 4. Gases are permitted to accumulate in the oxidizer until the desired pressure is reached, after which the pressure is maintained or regulated by controlling the discharge of gases through the valved gas discharge pipe 9. The pressure may vary considerably, say from 150 to 350 pounds per square inch. The preferred pressure will depend upon a number of conditions, including the temperature maintained, the kind of hydrocarbon mixture under treatment, the rate of air supply and, if oxygen-enriched air is used, upon the richness of the oxygen supply. It is preferred to carry out the oxidation process nder such conditions that the reaction is substantially self-sustaining. In general, the reaction is self-sustaining at a temperature of about 135-140 C., and at a. pressure of about250 pounds per square inch, with the hydrocarbon under treatment, although temperatures and pressures may vary between wide limits. Thus. for example, oxidation has been observed at a temperature as low as 100 (3.; it is more rapid above 120 (1., and the temperature may be allowed to rise to 155 C. with satisfactory results under some circumstances. Therefore, while I prefer to carry out the oxidation process at a temperature at which the reaction rate is fairly rapid, say 135-140" 0., it is to-be understood that the invention includes the employment of all suitable temperatures at which oxidation takes place. I During the oxidizing treatment, as .is

stated above, gases collecting in the upper end of oxidizer 1 are released through the pipe 9. These gases contain practically no oxygen, but do contain carbon dioxide, nitrogen and varying quantities of volatile acids, ketones and other products of the oxidation. The volatile acids, ketones and other products may be condensed in a suitable condenser not shown) and further treated for the recovery of formic acid, mixed light ketones, etc.

During the course of the treatment of the petroleum distillate in the oxidizer 1, there appear to be formed, during the earliest stages of oxidation, formic acid and hi h molecular Weight ketonic and/or aldehy ic bodies; continued oxidation results in the production of saponifiable water-insoluble carboxylic acids having molecular weights approximately one and one-half times those which would naturally be calculated for acids derived from the original (i. e. unoxidized) hydrocarbons. Prolonged oxidation converts these petroleum-soluble carboxylic acids into petroleum-insoluble hydroxy-carboxylic acids having about the same. or lower, molecular weights as those which would naturally be calculated for acids derived from the original hydrocarbons, low molecular weight ketonic and/or aldehydic bodies, water, and additional amounts of formic acid.

For the purposes of the invention, it is desirable to continue the oxidation treatment until the maximum amount of the petroleuminsoluble hydroxy-carboxylic acids has been obtained while avoiding undue decomposition of the hydrocarbons, as evidenced by an excessive amount of carbon dioxide in the effiuent gases and vapors passing to the condenser through the valved gas discharge pipe 9. Usually this occurs when the mass in the oxidizer 1 contains from 25-35% of petro leum-insoluble matter. At this point, which may be determined either by observing a sample of the massfromthe oxidizer, by titration, or by observations as to the time and rate of flow of the air for a given quantity of starting material and the undue increase in the relative amount of carbon dioxide in the efiiuent gases, the reaction mixture in the oxidizer l is discharged through the valved liquid discharge pipe 8 into the separating tank 12.

Upon settling, the reaction mixture separates into three layers. The bottom layer is found to consist of a strongly acid, aqueous solution of water-soluble acids together with some unsaponifiable matter which is soluble in this strong solution. This layer is drawn oil, through the valved conduit 14, into the acid water tank 21. The intermediate layer consists essentially of hydroxy-carboxylic acids which are insoluble in the reaction mixture, and the top layer is found to be a mixture comprising unoxidized petroleum, petroleum-soluble carboxylic acids, some hydroxy-carboxylic acids, and primary oxidation products, such as, for example, ketonic and/or, aldehydic compounds, primary and secondary alcohols, ethers, and possibly some esters.

After the settling has proceeded to the point where the supernatantoil is perfectly clear, the said .1: drawn by means of the swing suction 24, transferred through the valve conduitl i' to the petroleum distillate supply tank 15,

u and there mixed with fresh distillate in the I "the added'exciter of oxidation.

preferred proportions of 2: 1 for use in charging the oxidizer for a subsequent oxidation treatment. Said mixture, consisting of fresh distillate and material which has already been subjected to oxidation treatment, does not-require the presence of an oxidizing cat, alyst or exciter of oxidation to effect normal oxidation, the reaction proceeding in a manner identical to that-observable upon oxidizing a fresh charge of the distillate containing The residue in the separating tank 12, comprising saponifiable, petroleum-insoluble, wa

ter-insoluble,- hydroxy-carboxylic acids, is

then repeatedly washed with small quantities of water, which may be caused to rise to the top or settle to the bottom by appropriate control of the conditions. The wash water is found to contain some water-soluble compounds, and therefore preferably is transferred to the acid water tank 21 for the subsequent working up of values contained therein.

The water-free hydroxy-carboxylic acids are transferred from the separating tank 12, through the valved conduit 13, into the still 17 and are there subjected .to a vacuum distillation treatment for the removal of substantially all of those components which complete removal of volati'lizable tively higher temperatures are would evaporate -upon exposure of the prodnet to the atmosphere over protracted periods of time. The specific conditions under which the distillation is conducted depend largely upon the desired physical character of the end product, but in general the operation should be conducted at a pressure of about 10-20 mm. of mercury and at as low a temperature as possible for the substantially --e. g. from 140 to about 275 the production of hard, brittle products, while lower temperatures, with ingly increased yields, are suitable for the production of relatively softer and less brittle products. The volatilized material pass ing off from the still 17 under the influence of the partial vacuum maintained by the vacuum pump 20, and, preferably, assisted by a stream of air or steam admitted by the valved conduit 22, are condensed in condensp layer is carefully with-' for two days. Test thicknesses of the paper were prepared and their relative thickcompounds,

Test using natural shellac.

corresponder 18 and caught in the distillate receiver 19. The latter distillate contains volatile, esterifiable acids of lower molecular weight which may be worked up for the recovery of values .contained therein,-e. g. for the manufacture of esters,and heavier carboxylic acids.

which may be returned to the oxidation cycle through the valved conduits 23 land 14- for conversion into hydroxy-carboxylic acids. It 'isnoted that the carboxylic acids are "readily converted into resin-like products, whichcharacteristic apparently is due to the ease with which said acids polymerize. y i

The residue in thestill 17, obtained by the carrying out of the above-described procedure, is the shellac-like product which is the basis of the invention. In in color from amber to dark brown; usually, the lighter the starting material (i. e. the unoxidized petroleum hydrocarbon mixture) thelighter the color of the end product. The product, apparently an acid, or acid anhydride body, is readily soluble in warm caustic soda solution or sodium carbonate solution, by which it is saponi'iied to form soaps very similar to the soap produced by the saponification of natural shellac. It is insoluble in petroleum, in'the fatty oils, and other similar oils, but is soluble in carbon tetrachloride. Depending upon the conditions maintained during the vacuum distillation operation, it ranges in consistency from a hard, brittle, readily grindable solid to a relatively softer, tacky product. The softer, tacky. .varie-' ties are soluble in alcohol and in .benzol, whereas the hard, brittle varieties are practically insoluble in those solvents.

The chief characteristic of this product, from an economic viewpoint, is its high dielectric property. f

In order to arrive at a comparison of the relative dielectric properties of natural shellac and of the shellac-like product of the present invention, alcoholic solutions of the two substances were prepared by dissolving grams of each in 67 grams of alcohol. Sheets of common writing with'the solutions and then allowed to dry pieces, each being of four impregnated and dried general, 1t ranges 7 paper, averaging 0.0033 inch in thickness, were coated or impregnated Test laces using the shellac-like 5% -3 g pr uctot the present invention...

7.2 7.3 7.8 7.3 8.0 7.5 Test piecesusingnatural shellae.- 7.2 7.8 7.3 7.2 7.46 8.2

Unlm re ated a er test pieces..-

gn pp 2.9 2.7 2.9

ameter and ointed at the end adjacent the test iece. t the same time the results were chec ed against the dielectric. capacity of four-thickness test pieces built up of the uncoated or unimpr-egnated paper.

The following values were obtained:

Dielectric capacity, measured ta kilovolts It should be noted that the test pieces using the shellac-like product, although somewhat thinner in cross-section than those using natural shellac, were found to have a higher dielectric capacity than the latter.

The tests demonstated the fact that the shellac-like, product of the invention,although stickier than the natural product,- has a higher melting point than that of natural shellac.

The above tests are summarized as follows:

Average thickness K'] K F J W Average of test piece of paper agg dielectric dielectric ingle impregnated withcapacity capacity c p city 0! thickness of mink of test piece test piece of paper Dreenated g g g t e it Natural l i'gr iiire Shem)- producishenac cunt s trials Average Average of Product 01 15 trials 16 trials Inch Inch K c. K 0. l K 1'. 0.0033 0. 0417 Q. 0391 3. 854 7. 687 8. 37

The shellac-like product above described is adaptable for use in all insulation applications in which shellac is used. For example, it may be admixed with wood flour, asbestos, mica, wood pulp, or other inert materials in the same manner, and in about the same proportions in which shellac is used, for the production, under conditions of high temperature and pressure, of molded insulation,

' hard, dense and homogeneous, may be sawed,

nailed, turneil, and generally worked in the same manner as a natural hard wood.

In substantially the same manner, there may 3e prepared molded articles containing -65% of asbestos, 85-7 0% of mica, or 50% of wood pulp admixed with said shellac-like product. In molded compositions such as those just mentioned, as well as in the composition forming the subject matter of the above example involving the use of wood flour, I have found that the shellac-like product advantageously may be used in the form of a salt,as, for example, the calcium salt, of the petroleum-insoluble hydroxy-carboxylic acids, in which form the product readily may be ground and admixed with the inert materials.

Also, it may be introduced, in finely divided condition, into paper pulp in the heating engine, for. the production of a stilt, hard paper'having high dielectric properties. In the form of a sticky, highly viscous product it may be used for the impregnation of tape for electric insulation, producing thereby a highly dielectric tacky tape which sticks well to the wire or to itself.

The shellac-like product, hereinbeforc described, may be dissolved in suitable solvents to the production of a solution adaptable for use as a substitute for the commonly used solutions of natural shellac.

It is noted that the hard, brittle, shellaclike product above described may be prepared by merely exposing the etroleum-insoluble, saponifiable hydroxy-car oxylic acids, as obtained by the separation operation in separating tank 12, in thin films to a current of air at room temperature or thereabouts. However, such procedure is uneconomical in view of the fact that the valuable volatilizablc compounds contained in the intermediate product thereby are lost.

'hile in the foregoing-description the production of my shellac-like product has been described by reference to a batch process, it is to be understood that the invention is not restricted thereto, and that the process of making said product might well be carried out by recourse to a continuous or cyclic proceduro, involving the controlled oxidation of a moving body of oil, continuous separation of the petroleum-insoluble hydroxy-carboxylic acids from the reaction mixture, and continuous return of unoxidized oil and partial oxidation products to the oxidizer.

While the production of the hereinbefore described shellac-like product is not restricted to any particular theory of oxidation reactions, the following is advanced as being a probable explanation of said reactions.

In regard to the reactions which may take place during the controlled oxidation of petroleum hydrocarbon mixtures by means of air under pressure at reacting temperatures, it is thought that the main primary reaction is one in which the oxygen attaches itself to a secondary carbon atom in the hydrocarbon chain and, in general, it is believed that the first secondary carbon atom after the primary carbon atom,in other words the carbon atom in the ,B-position to the CH group at the end of any chain or branch,is the one to llll Ill

Ill

whichthe' oxyg the opinion, from. ."many observations, that the oxygen isabsorbed without thelossof any hydrogen; in other words, 'ajhydroxyl "group is formed at this point,vthus forming a secondary alcohol.

The principal reason raistaingtha this is the case is the fact that with'the oxidation of a given mass of petroleum there i obtained as high as of formic acidi an it isbe lieved that this is .due to theejndhydrocarbon radical being eliminated in the "form. of-formic acid by'the oxidation of ;a:ketoneformed from the secondary alcohol in'which the hy 15 droxyl is attachedto the I? )3" carbon "atom.

go the methyl group is on one side of, the CO larger molecule, the CO group thus becoming The above conclusion is supported by the fact that when asecondary alcohol is oxidizedit first forms a ketone. Then a ketone which is a methyl X ketone-that is,'oneinfwhich group and a group of very much higher molecular weight is on the other sidefof the COT:

molecularyweight, lti's -probable that there group,-such ketone oxidizesinsuch manner as to leave the CO group attached to the;

the vcarboxylic group of the high molecular weight acids and the OH, group forming formic acid. The rule in other words is that when ketones are oxidized the CO group attaches itself to the radical of higher molecular weight and the group of lower molecular weight is oxidized to the corresponding acid containing only the total number of carbon atoms which that group has minus the CO group.

This view is further supported by the-fact that of the oil remaining after removal ofv all'easily volatile and all acid products the greater proportion forms crystalline compounds with bisulphite. indicating the presence of rather large amounts'of ketones or aldehydes but, as before stated, the opinion, inclines to the formation of ketonesratherthan aldehyd es because of the ve I duction of formic acid.;.- ered that one is treatingfhy an average composition} that one obtains as high formic acid thereseemsto explanation for themain up p l'reaction. It has been found alsotha-t' themixture of acids produced under conditions tending 'to avoid production of hydroxy-acids shows a molecular weight which' i'nmost cases, corresponds to hydrocarbons of'about 50% higher molecular weight than ,those chosen for the oxidation. This may be accounted for in two possible ways; There may be incipient oxidation in the end hydrocarbons,-that is, of the methyl group of the hydrocarbons,in such a way as to effect what is known as the Kolbe reaction. If simultaneously, by an atom of oxygen, two hydrocarbon molecules are so oxidized that the methyl group, in the case of each molecule,

att'ac esitself; It i's;

l syn'thesis imme .t'ronFl'nolecules formingone of twice the molecular weight less two hydrogen atoms.

leumsinsoluble hydroxv-carboxylic wouldvery naturally be the case. since loses: one hydrogen atom, one would have a lately of the. two hydrocar- Theotherpossible explanation, which would cases one'f'w'o'uld have at the other end of a straight chain, or at any other branch, a car bon atomqin relatively the same position as the first secondary carbon atom which had been oxidized to ketone and acid which also would bejoxidized, probably almost simul- ,taneously,fto an alcohol. The acid in one casewould either form a lactone with itself formant ester with the alcohol at the same chain in another molihe orrpther acid, thus formn I idna-ndya sthe acids of lower l'e larwei'ght arefrequently much more active in ester} formation than those of higher would be a'synthesis .of this kind producmgj-an average molecular weight of about 50% higher value than the simple acid theory would account for.

It seems proper to infer, from the above theory, that the oxidation relations occur in such manner that very large molecules are formed by the esterification of hydroxy-acids by acids of th lower, molecular weight, thus forming almost endless chains. Separations by partialfprecipitation have obtained from acids which show an average molecular weight of about 360. acids having molecular weights as high as 800 and, from the same mixture, there have been precipitated acids havin molecular weights as low as 100. This is particularlv time where the oxidation has been carried far enough to form petroacids.

rjiiolvmerizati on either through esterizaon or through po'lvmerization due to the fact thatthey have the hydroxv group. This hydroxy groupalso may readily become a ketone group, as is readily perceivable. Ketones in themselves, are also extremely active: espe- -{cia1l-y.'the higher keto es show a great tend-. encv to polvmerize.

This mav be an added cause for the production of acids of extremely high molecular weight.

An additional fact which supports the idea of ester acids or ketone acids being formed is that, if these hi her molecular weight acids are distilled without too much destruction, there are obtained mixtures of lower molecular weight acids and ketones with some small quantities of hydrocarbons. The principal amount of material, however, comprises acids e same, or higher, or

of lower molecular weight than those put in the still and ket'ones of not very high molecular weight. This would appear to support the ester acids hypothesis.

This application contains subject matter in common with my applications: Serial No. 588,073, filed Sept. 13, 1922; issued Nov. 6, 1928, as U. S. Patent No. 1,690,768; Serial No. 642,638, filed May 31, 1923; issued Nov. 6, 1928, as U. S. Patent No. 1,690,769 and therefore is a continuation in part of said applications.

I claim:

1.- Process which comprises contacting a free oxygen-containing gas with a mineral oil product consisting essentially of relatively low molecular weight, normally liquid, aliphatic hydrocarbons, in liquid state, at a reactive temperature of from about 100 to about 155 C., and at a pressure of from about 150 to about 350 pounds per square inch, in the presence of an excit-er of oxidation. continuing the oxidation treatment until the re action mixture contains a material amount of hydroxy-carboxylic compounds insoluble in petroleum and in the reaction mixture and removing more readily volatilizable products therefrom.

2. Process which comprises contacting a free oxygen-containing gas with a normally liquid petroleum distillate having a density of from about 40 to about 36 Baum. in liquid state. at a reactive temperature of from about 100 to about 155 (3., and at a pressure of from about 150 to about 350 pounds per square inch, in the presence of an exciter of oxidation, continuing the oxidation treatment until the reaction mixture contains a material amount not substantially in excess of about 35% of petroleum-insoluble hydroxy-carboxylic compounds. separating the said acid compounds from the said reaction mixture and removing more readily volatilizable products therefrom.

- 3. As a new product a material comprising saponifiable. water-insoluble hydroxy-carboxylic acid compounds insoluble in petroleum and in fatty oils, soluble in carbon tetrachloride and in solvents for natural shellac, which material possesses dielectric properties at least equal to those of natural shellac and when free from all volatilizable compounds is a hard brittle solid, which material is obtainable by contacting a free oxygen-containing gas with a mineral oil product consisting essentially of relatively low molecular weight, normally liquid, aliphatic hydrocarbons, in liquid state, at a reactive temperature of from about 100 to about 155 0., and at a pressure of from about 150 to 350 pounds per square inch, in the presence of an exciter of oxidation, continuing the oxidation treatment until the reaction mixture contains a material amount of petroleum-insoluble hydroxy-carboxylic acid compounds and separating the 4. As a new product a material comprising saponifiable, water-insoluble hydroxy-carboxylic acid compounds insoluble in petroleum and in fatty oils, soluble in carbon tetrachloride and in solvents for natural shellac, which material possesses dielectric pro erties at least equal to those of natural she lac, and when free from all volatilizable compounds is a hard brittle solid, which material isobtainable by contacting a free oxygen-containing gas with a normally liquid petroleum distillate having a density of from about 40 to about 36 Baum, in liquid state, at a reactive temperature of from about 100 to about 155 0., and at a pressure of from about 150 to about 350 pounds per square inch, in the presence of an" exciter of oxidation, continuing the oxidation treatment until the reaction mixture contains a material amount not substantially in excess of about' 35% of petroleum-insoluble hydroxy-carboxylic compounds, separating the said acid compounds from the said reaction mixture and removing more readily volatilizable products therefrom.

In testimony whereof, I afiix my signature.

ARTHUR W. BURVVELL. 

